Field: Conveyor system transport equipment such as belts, chains, cable, and rope, particularly conveyor belts of the lengthy and endless type used to transport material such as coal, minerals, products or the like over long distances typically comprise a drive roller means, a tail roller means, and a belt means, typically in 500-1000 ft., sections for long heavy duty belts, with their ends connected (spliced) to make the belt endless. Such belts are used to convey thousands of tons of material or product per hour. These belts range from one or two feet in width up to seven feet or more in width and are up to three or more miles in total length with several sections of belt spliced end to end with riveted metal splices or cured rubber splices, or other such means.
Coal mines and quarries, for example, typically use long, wide conveyors that carry thousands of tons of material at one lap of the belt. Obviously, proper maintenance of these belts is critical to maintain desired production rates and to limit conveyor downtime, which can be several hours for severely damaged or separated belts. In the use of such long belts, damage areas such as rips, tears, holes, broken metal splices, partially tom apart splices and the like often occur and must be repaired quickly if a complete breakage and separation of the belt is to be avoided, and if an economical transport or production rate of the conveyor is to be maintained or restored.
In this regard, and as shown in FIG. 6, the present invention provides an application relating to conveyor belt scrapers. In underground coal mines, for example, belt scrapers are installed, typically at belt discharge points, to scrape material from the belt to prevent its being carried back on the return belt section. These scrapers are made in many different structural compositions, designs and configurations, however, because of federal laws and the labor required to clean up xe2x80x9ccarry backxe2x80x9d , belt scrapers with tungsten carbide blades are widely used. These scrapers are installed to scrape the belt with heavy pressure and because of this the scrapers do a lot of damage to the mechanical and vulcanized splices as well as the mechanical splices themselves damaging the scrapers. With the present invention it is possible to know when a splice is coming to a scraper and then to lessen the pressure on the scraper to prevent or minimize damage to a splice and to the scraper.
As further background, such long coal mine conveyor belts, being made of stretchable material such as polymer or steel belt or steel cable reinforced tire cord, must be placed under very heavy tension between the drive roller means and the tail roller means by, e.g., hydraulic tensioning apparatus in order to provide an adequately deformation resistant support surface and to prevent belt slippage on the drive roller means. As a consequence, for example, when a damaged splice is to be repaired and requires the belt section to be separated at the splice, the aforesaid tension must be removed which can shrink the length of the belt by several feet. Heavy clamping and other equipment must therefore be used to support and hold the adjacent ends of the belt sections into a precise position against the shrinkage forces such that the splice can either be repaired or replaced. A very convenient location for a repair station is in proximity to the accessible drive end of the conveyor.
The above described damage areas which may not have resulted in a complete separation of the belt, are primarily what the present invention is directed to. It is noted that for the worst scenarios such as a complete breakage and separation of the belt deep within the mine, the repair station with all of its heavy attendant equipment necessary to pull the untensioned and shrunken belt back together to make a new splice, would have to be transported to the break site. It is noted that in describing herein the various applications of the present invention, the term xe2x80x9cevent sitexe2x80x9d is used to indicate undamaged splices, damaged splices, splices about to arrive at a scraper station, tears, rips, bulges, or the like in the belt, or any other site on or in the belt which may need instant or future attention from maintenance crews.
Prior Art: Heretofore, the detection of an event site, visually or otherwise, often has been only the first step in a very time consuming process for bringing the site to a location where, e.g., repair of belt tear damage is feasible. For example, in long coal mines where the conveyor extends many thousands of feet, e.g., 3,000 or more, in low light and cramped conditions, the damage site may be detected on the fast moving conveyor, e.g., 10-15 mph or more, but controlling the motion of the enormously heavy belt such that the damage site can be brought to a stop at a convenient repair station after a deceleration slowing down period is very difficult. The massive momentum of the belt, especially when loaded, prevents any rapid stopping of the belt and over running of the damage site beyond the repair station often dictates that more than one complete and time consuming lap of the long belt will be needed to bring the damage site again to a desired repair location where the heavy and specialized equipment for handling the belt is available.
Principal objects therefore, of the present invention are to provide a method and apparatus for monitoring damage or other event sites on a conveyor belt and controlling the running of the conveyor such that a spotted event site on the moving belt can be quickly brought to a desired repair location, whether inside or outside a mine or quarry or the like, and/or to provide a monitoring system for the location of splices (event sites) in the moving belt relative to the position of belt scrapers whereby the belt scraper pressure can be quickly but temporarily relaxed as the splice is moving by the scraper to avoid damage to the splice and/or scraper.
The above and other objects have been attained in accordance with the present invention, which in one of its preferred method embodiments is designed for facilitating the maintenance of long, heavy conveyor belts of conveyor systems and comprises the steps of (a) monitoring a conveyor belt for event sites (ESL), (b) spotting an event site and logging into computer means sufficient data from which the computer means determines and records the location of the event site (ESL) on the belt, and (c) using the recorded event site location data to control operational aspects of the conveyor system components, e.g., belt speed or belt scraper pressure which affect the maintenance or condition of said event site.
In another preferred embodiment the method comprises the steps of providing a conveyor structure having a continuous conveyor belt which is mounted on roller means mounted on base means of said structure, providing one or more counter means on said conveyor structure for measuring the distance traveled by one or more designated cycle points (CP) fixed in position on said belt, providing one or more reset means for resetting said counter means to zero each time a designated cycle point travels a measured cycle with respect to a designated fixed zero set point (ZSP) on said conveyor structure, spotting an event site (ES) in the travelling belt and immediately transmitting a xe2x80x9cDBZxe2x80x9d reading (i.e., the distance the event site has traveled beyond a designated zero set point at the moment of spotting) to computer means which calculates the distance the event site has to travel to arrive at a designated repair station, and providing this data to an operator or an electronic motor controller such that the operator or motor controller can control the conveyor drive motor speed to stop said event site at said designated repair station.
In another and highly preferred embodiment, the aforesaid counter means provides a substantially continuous visual display of the remaining distance which the event site has to travel to reach the repair station, whereby an operator can readily determine when and how fast to decelerate the drive motor to stop the event site at the repair station.